CHAPTER IV 



THE NERVE-MUSCLE PREPARATION 



THE central nervous system of a frog is destroyed by cutting through the spinal 

 cord at the occipito-atlantoid ligament and passing a blanket pin into the skull 

 and down the cord. Notice that the muscles of the trunk and limbs are thrown 



Cut pectoral girdle - "\C~J 



Small intestine 



Testicle. 

 Rectum. 

 - Bladder. 



FIG. 27. VISCERA. OP FROO. THE LIVER is SHOWN IN OUTLINE, AND THE 

 PARTS CONCEALED BY rr ARE INDICATED BY DOTTED LINES. 



into contraction when the cord is being destroyed. Make a circular incision 

 round the trunk just below the upper limbs through the skin only, and, seizing 

 the skin covering the lower part, strip it off from both hind limbs. Lay the frog 

 on its back on a glass plate, and open the abdomen and thorax freely but care- 

 fully. Notice the viscera (fig. 27) heart and lungs, liver, stomach, intestines, 



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